Apparatus for concentrating solutions



March 9 1926. 1,576,136

M. o. JOHNsoN APPARATUS FOR GONGENTRATING SOLUTIONS Filed Sept. 19, 19213 Sheets-Sheet 1 /A/ V NTOR t mi@ O, IF

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ATTRNEY March 9 1926. 1,576,136

M. o. JOHNSON APARAIUS FOR CONCENTRATING SOLUTIONS Filed Sept. 19, 19213 SheetS-Sheet 2 BRINE TANK COMPRLSSOR RECEIVER A T RNE Y Marchy 9 1926.

Mv O. JOHNSON APPARATUS FOR GONGENTRATING SOLUTIONS 1921 3 Sheets-Sheet5 Filed Sept. 19

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l! [lill TOR Loc ooooooo Patented Mar. 9, 19.26.

UNITED STATES MAXWELL O. JOHNSON,A OF WAIPIO, TERRITORY 0F HAWAII-APPARATUS FOR CONCENTRATING SOLUTIONS.

Application led September 19, 1 921. Serial No. 501,855.

To all whom z't may concern;

Be it known that I, MAXWELL O. JOHN- soN, a citizen of the UnitedStates, residing at VV-aipio, in the county of Honolulu, Territory ofHawaii, have' invented certain new and useful Imprpvementsin Apparatusfor Concentrating Solutions, of which the following is a specification.I

llhe invention" relates to a novel meansfor concentrating solutions, andmore particularlyto such a means wherein the concen-- tration iseffected by freezing, and regenerative features, or steps and means areemployed.

Objects and advantages of the invention will be set forth in parthereinafter and in part will. be obvious herefrom, or may be learned bypractice with the invention, the saine being realized and attained byvmeans of the instrumentalities and combinations pointed out in theappended claims.'

The invention consists in the novel means, parts, constructions,arrangements, steps,

.improvements herein shown and described.

Theaccompanying drawings, referred to herein and constituting a parthereof, illustrate exemplarily the present preferred form of means orapparatus employed 1n carrying out `the invention, and illustratecertain steps in the method or process; the d rawings being 4more orless diagrammatic in character.

Fig. 1 -is a transverse vertical section of one form of freezing andconcentrating apparatus included in the invention;

Fig. 2 is a like vertical section of a somewhat different form of suchapparatus;

Fig. 3 is a similar view showing a yet different form of such apparatus;

Fig. 4 is a diagrammatic elevation show-- ing.;r the regenerative stepsin the process and the apparatus preferably employed in connectiontherewith; and

Fig. 5 is a diagrammatic elevation, ona smaller scale, of the same stepsand a paratus, but showing certain parts in a dition to those shown inFig. 4. l

The concentration of solutions of many various kinds and constituentsare widely and generally effected by evaporation. and usually involvethe application of relatively high temperatures. This""type of processis objectionable in case of very many solutions and for a number ofreasons. This application of heat, especially at high temothers.

peratures, and for relatively long periods,

is very injurious to many solutions, and partici'ilarly to organicsolutions such as fruit juices, milk, dye-wood extracts, and many Inthe-case of many such solutions the em loyment of relatively hightemperatures e ects decomposition or dissociation of some of the highlyorganized compounds' essential to or characteristic ofthe solutions. 1twill be understood that the term solution herein is usedgenerally todesignate" any relatively dilute liquid to be concentrated, and the termsolvent to indicate the diluent, that is the part thereof which isseparated out by the freezing action in order to concentrate the liquid.

These evils and disadvantages are obviated in concentrating by freezing,and this process usually improves or maintains the quality of theYoriginal solution in the concentrate, as it avoids the breaking down ofthe highly organized compounds characteristic of the solutions, andavoids foaming and other'evils.

In connection with the freezing process also, certain features of easyand rapid separation of theconcentrated .fluid are realized,

together with capacity for maintaining Ya f I lcontinuous process, andalso for employing regenerative steps or means which render the processeasy, rapid and economical.

Referring now in detail to the present preferred manner of carrying outthe process and the present preferred form of apparatus, and referringfirst to the direct step of freezing to concentrate the solution and toeffect separation of the frozen solvent and of the remainingconcentrated liquid, the

process is primarily described as applied to aqueous solutions, such afruit juices, although it will be understood that in its main featuresthe invention isv applicable to the concentration of otherkinds ofsolutions.

By my. invention, an apparatus is provided for freezing a solution in acan, tank or other suitable container of heat-conducting materia-l, onelevel or portion of the container being subjected to freezingtemperature, and another level orcpoi'tion being maintained above thefreezing temperature, the aqueous or other more dilute part of thesolution being frozen Within the con- I tainer, and the condensedresidue ofthe solution 'collecting in that part of the container whichis maintained above freezing temperature.v As embodied, a refrigeratingmedium is applied to the exterior of a. part of the can or compartment,and preferably to the upper part thereof, and the lower part ofthe canor container is maintained above the freezing temperature. The aqueousor other thin part ofthe solution in such a can or container under thesecon-- ditions, will freeze out in an almost pure condition as ice on thesides or walls of the container, while the concentrated 4solution, W ichis of greater specific gravity than the dilute solution, will settleinto the bottom or non-freezing portion or part of the container.

When the desired or required4 degree of concentration is reached, theconcentrated fluid or solution may be drawn off without disturbing theice or frozen original dilute solution. j

This will remove the greater part of the concentrated solution, but byallowing the portion of the can or compartment which was subject tofreezing to lrise in temperature above the freezing point, the ice inthe can will gradually thaw or melt, and the remainder of theconcentrated part-of the solution (which is of intermediateconcentration betweenk the very dilute and highly concentrated parts)will come ofi' in the f irst drainin as it forms a softer or mushier iceo'r ike solid. Practically all of 'this string concentrated solution maybe drained off before the pure or harder ice begins to melt and at thistime almost pure ice is leftin the can or container, and theconcentrated juice is practically entirely drained off, thus effectingan easy, rapid, economical andcomplete separation of the two.

If desired, the blocks of ice formed in the can may be thawed loose,lifted out7 broken up and Acentrifuged to recover the relatively smallresidue ,of concentrated juice. This, however, is usually unnecessarywhere the draining, thawing and again draining process as just describedis employed. The pure ice secured may be broken up and f used in theregenerative process hereinafter described.

Referring now in detail to Fig. 1 of the drawings, a can 1 of sheetmetal or other highly heat conductive material is employed as acontainer for the solution to be concentrated. I have found that themost eiiicient form of can is one which is relatively deep verticallyand of comparatively small horizontal cross-section. This permits abetter and more efficient heat interchange Withthe circulatingrefrigerating medium,

The can may be of any suitable or desired form, but is preferablyrelatively narrow and deep, and rectangular, oblong orr cylindrical inhorizontal cross-section. Means are provided for applying arefrigerating medium, and preferably a'circulating refrigerating medium,to a portion of the exreater part of thepart of thejacket may beconveniently termed the' freezing portion, and the portion 5 thereofexternal to and belowthe jacket 2 may be termed the non-freezingpor-tion of the can. The lrelative size of these. portions will dependpartly on the degreefof concentration desired. Usually about one-half totwothirds of the water in a solution is as much as it is convenient toremove in one oper-l ation. A ratio of about four or five to one betweenthe freezing and non-freezing portions of the can or container isapproximately correct and efficient for this amount of concentration'.This also allows or causes a core of concentrated solution to extendthrough the center of the can, as shown in Fig. 1, and shortens the timeof Vfrcezinfr o b l since the ice need not be frozen solid through thediameter of the can 1 to effect the desired concentration. o

Means are provided for diainino` off the concentrated solution', and asembodied a pipe 6 communicates with the bottom of the can 1, and isprovided with a valv'e 7.- Any suitable supply may be provided for thedilute solution, and the process may be practically continuous. It willbeunderstood that the ice must be periodically removed, which can beaccomplished by slightly thawing and then liftin out the ice block, andthis may be done either with or without the step of thawing to ,recoverthe remainder of the concentrate as ,already described.

In Fig. 2 a Vertical section is shownthrough a somewhat different formof can kor tank. In this form, the can or tank 10 is one of a series,and rests on `supports 11` and 12. Between this can 10 and the adjoiningcans are spacing blocks 13 and 14, resting upon the blocks or supports11 and 12. Over these blocks and around the can 10 there is poured orplaced a waterproof, heat insulating compound or material 15, such aspitch, or any other suitable inate.'ial. This is filled in to such adepth as will give the desired proportion between the freezing andnon-freezing portions of thecan or tank 10, as already explained inconnection with Fig. 1. l

The cans or tanks 10 are separated at or near their top by means of bars16 and 17,. Through the spaces 1K8 between the cans' or tanks, therefrigerating medium, such as cold brine, is circulated in the samemanner as within the jacket 2 of the can or tank of F ig. 1. Suitableinlets and outlets (not shown) will be provided.

In this figure, hooks 19 and 20 are shown which are connectedby a crossyoke 21 and are suspended from the top edges of the can by their hookends 22, and become imbedded in the ice during the freezing operation.An eye 23 is formed in the cross ban 21, to lwhich 'a hook or otherdevice may be attached to lift out the cake of ice after it has beensuiiiciently thawed. The pipe 24 communicating with the bottom of can 10serves for the drawing olf of the con.-

centrated liquid in the bottom of the can, and is provided with a valve25.

IVitli the construction of the can or tank just described, thedifference in level and relative position of the freezing and non'-freezing parts of the can or tank are dependent on the difference inspecific gravity of the dilute solution and the concentrated solution,the latter being the heavier. If in any case the concentratedliquidshould lighter, the' parts of the can would reversed. The cans ortanks may be provided with suitable closures, not shown.

In Fig. 3 a form of tank or can 30 is shown, adapted to be suspended ina brine tank which may be of the usual form. The

tank 30 is suspended by a ring 31 around the top edge thereof, restingupon a plate or supports 32 supported on the tank structure.

The non-freezingpart of the can or tank 30 is provided in this case by alayer or layers 33 of heat-insulating material, such as sheet cork orother suitable material.

A pipe 34, provided with a cock 35, serves to drain the concentratedsolution from the can. If desired the can may be lifted from the brinetank and the concentrated solution may be poured out through the top ofthe can. This form of can, while adapted for use with a common orstandard type of brine tank, is usually not as efficient as the twoforms previously described, as some heat may be transmitted through thcinsulation 33 and as a consequence some mushy ice may be formed in theconcentrated solution, thereby rendering the separation more dificult.

lVith certain kinds of solutions the separation is more effectively-accomplished by agitation, and 4this may be e'ected by any known orother suitable means, such as a stream of air, a circulating pump, arotating screw, or other suitable means.

With vcertain solutions, such'as fruit puces forexample, agitation maycause foaming and be objectionable on this account.

Referring now more particularly to the regenerative or energy conservingfeatures of the invention, it may be stated generally that the iceformed during the concentrating process is employed ory consumed incooling the ammonia, or other refrigerating medium, to effect or assistin el'ecting'tlie required reduction iny temperature, and it is alsopreferably employed to pre-cool the dilute solution, that is to cool itpreparatory to concentration. As one feature of the regenerativeorenergy-saving process, the coId concentrated solution is also preferablyem-` ployed to pre-cool the dilute solution.

In the preferred embodied form thereof, it is shown` applied to arefrigerating system of the ammonia compression type, as this is thetype in most common use, but it will operate equally Well with othertypes of refrigerating systems and other refrigerating media besidesammonia; or will operate with the ammonia absorption type or system, asthe condenser or expansion coils.

'lower a solution to its freezing point is small compared to thecapacity required to freeze out the solvent. If the ice be utilized incooling the condenser of the refrigerating apparatus, the refrigeratingwork o-r energy expended in freezing the ice is returned to the system.Thus aside from radiation and mechanical losses, the only capacityrequired of the refrigerating apparatus is the small amount necessary tolower the temperature of the dilute solution to the freezing point..

The cooling ofthecondenser by 'the ice will lower the condensingpressure' in the refrigera'ting apparatus very materially. Theefficiency of a refrigerating apparatus is proportionately greater theless the difference between the. condenser pressure and the low orexpansion pressure. By melting the ice which was formed in theconcentration process in the operation of cooling the condenser, agreatsaving is secured or eifectl ed in the amount of energy required tooperate the refrigerating apparatus; or the same refrigerating apparatusmay be made to furnish increased capacity or roduct with the same energyconsumption. 3y utilizing the outgoing cold concentrated soluf tion. andalso the ice to cool `the incoming dilute solution an additional,vsaving is efl fccted.

The mat-ters of tlieoiy just stated are true and ap licable to the bestof my present knowle ge and experience, but it will be un-`refrigerating apparatus.

derstood that the invention is not ai'ected should any errors ordiscrepanciesbe later vfound therein.

is supplied from a centrifugal, or ice-breaker, operating inconjunct-ionwith the concentrating apparatus) dumps or poursl the brokenice. over the coils 41 of the condenser. The ice is rapidly melted bycontact with the coils 41,`.and thel water is drawn oif through anoverflow pipe 43. A baffle plate 44 may be employed to`keep the outletclear.

Usually the hot ammonia Agas from the compressor passes into thefore-cooling coils 46, which coils are cooled by water runningthereover, and if desired, this may be the water from the melted ice inthe tank 40. Thus a considerable portion of the heat of compression isremoved from the gas by this apparatus. `The supply of water to theco'il 46 is regulated so as to give a low condensing pressure, but notso much so as to cool the compressed gas so that it cannot l melt allthe.ice around the submerged condensing coils 41. The gas at thisdesired temperature asses from the cooling coils 46 by pipe 47 t roughcheck valve 48 into the condensing coil 41. The liquid ammonia passesthrough the pipe '49 to the receiver.

Referring now to the pre-cooling ofthe dilute solution, in accordancewith vcertain features of the invention, this is effected both by theaction of the oold condensed liquid and also by the action of the ice.or frozen solid. AS embodied, the cold concentrated liquid entersthecounter-current apparatus 52 through a pipe 53, and passes outtherefrom through a pipe- 54. The dilute solution to be cooled entersthe counter-current apparatus 52 through a pipe 55, and passes outtherefrom through a pipe 56. Thus some portion of the heatis abstractedfrom thewarm dilute solution bythe cold concentrated solution in ythecounter-current apparatus. l Y f In the' embodied` manner of utilizingthe ice or frozen solid to cool the dilute solution, pipe 56communicates with a pipe or pipe coils 57, over which the ice from theconveyor 42 passes to the condenser coils 41. The coils 57 are above thesurface of the liquid in tank 40, and are spaced relativel far'I therapart than are the condensing coils 41.

.pipe 58 to the cans or tanks, previously de- There is thus no tendencyfor the ice to block or hang on the coil 57 since it is beingmelted'below by the coils 41. The cool dilute solution passes from coils57 through a scribed, for the freezing concentration process.

The concentrated solution and the melted ice or solvent, that is,thewaterV from the tank 40, leave the system but little below ordinarytemperature, and thus their low temperatnres,"imparted during theconcentration process, have been transferred very largely to` therefrigerating means and to the dilute solution, and but very littleadditional refrigerating capacity .or energy need be added or suppliedto the system or cycle to keep it in operation.

The invention in its broader aspects is not limited to the precise formof apparatus shown and described, but changes may bemade therein withoutdeparting from the principles ofy the invention and without sacrificingits chief advantages.

1. An apparatus for concentrating solutions by freezing, comprising incombination a freezing tank, a compressor', a forecooler, means forfurther cooling the compressed refrigerant with ice from the freez ingtank, means forl expanding the refrigerant, means for extracting heatfrom the freezing tank through the medium of the expanded refrigerant,means for drawin off lthe cold unfrozen concentrated solution rom 100the freezing tank, means for conducting dilute solution to the freezingtank, and a heat exchange device in which the incoming dilute solutionis pre-cooled bymeans of the outgoing cold concentrated solution.

2. An apparatus for concentrating solutions by freezing comprising incomblnation a freezing tank, a compressor, a' fore-cooler, means forfurther cooling the compressed refrigerant with ice from the freezingtank, 1,10 a brine tank, means for expanding the refrigerant and coolingthe brine and appl ing the cooled brine to the freezing tank means fordrawing off the cold unfrozen solution from the freezing tank, means forleading the dilute solution `lto the freezing tank, and a heat exchangedevice for cooling the incoming dilute solution by bringing it into.heat -interchangin relationship with the outgoing cold un rozenconcentrated solution.

3. An apparatus for concentrating solu` tions bfreezing comprising incombination-a reezing tank, a compressor, aforecooler, means for furthercooling the compressed refrigerant with ice from the freezlng tank, abrine tank, means for expanding the refrigerant and cooling the ybrineand applying the cooled brine to the freezing tank, means for drawingolf-"the cold un- 13 tionship With. the outgoing'cold unfrozen drawing ofrozen solution from the freezing tank, means for leading the dilutesolution to the freezing tank, a heat exchange device for cooling theincoming dilute solution by bringing it into heat interchangingrelaconcentrated solution, and means for additionally cooling theincoming dilute solution With ice from the freezing tank.

Ll. An apparatus for concentratingsolutions by freezing comprising incombination, a freezing tank, a compressor, a cooling tank containingice from the freezing tank, for cooling the compressed refrigerant fromthe compressor, means for cooling the compressed refrigerant before itenters said cooling tank, with Water obtained from the melting of theice in 'the cooling tank, means for the ycold unfrozen solution, meansfor supplying dilute solution to the freezing tank, a heat exchangedevice through which the cold unfrozen solution and the incoming dilutesolution are passed, for pre-cooling the incoming dilute solution, abrine tank, means for expanding the refrigerant and cooling the brineand applying the cooled brine to the freezing tank for freezing thecontents thereof, and means for additionally cooling the incoming dilutesolution With ice from the freezing tank.

5. An Vapparatus for concentrating solutions by freezing, comprising incombination a freezing tank, a brine tank, means for` ,subjecting theupper part only of the freezing tank to the cooling action of thebrine', a compressor, a forecooler, a cooling tank for the compressedrefrigerant, containing ice from the freezing tank for 'further coolingthe compressed refrigerant, means-for expanding the cooled refrigerantand cooling the brine therewith, means at the lower part of the freezingtank for conducting away the cold unfrozen solution, means fordelivering dilute solution to the freezing tank, and a heat exchangedevice through which the dilute and concentrated solutions lare passed,for pre-cooling the dilute solution. In testimony whereof, I have signedmy name to this specification. y

MAXWELL O. JOHNSON.

